Impulse measuring and recording apparatus



p 1941 T. A. RICH IMPULSE MEASURING AND RECORDING APPARATUS Original H166! Nov. 26 1938 Inventor: Theodor-e A. Rich,

WCx/ M by His Attorn g.

Patented Sept. 9, 1941 FE'EQE.

Ell/ PULSE MEASURING AND RECORDING APPARATUS Theodore A. Rich,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York 4 Ciaims.

guide him in his work and to assure that the r Welding operations meetthe exacting specifications necessary for reliable work. The mostimportant factors are the heating rate of the welding current and itsduration, the pressure and area of electrodes, and the conditions ofsurfaces. The measurement and control of pressure, area and surfaces isreadily measured by commonplace means. The device here describedmeasures the ampere-s uared seconds of the Welding current. v

This application is a division of my application Serial No. 242,543,filed November 26, 1933, on an Impulse measuring and recordingapparatus. Said parent application contains claims directed primarily tothe subject matter of the novel galvanometer recorder described herein.The present application contains claims directed to a novel timingcontrol for the galvanometer recorder. Another divisional applicationfiled concurrently herewith contains claims directed, to certain novelfeatures of the recording appa ratus described herein.

The features of my invention which are believed to be novel andpatentable will be pointed out in the claims appended hereto. For abetter understanding of my invention reference is made in the followingdescription to the accompanying drawing in which Fig. 1 represents .awiring diagram in which my improved measuring and recording apparatus isshown in perspective and is arranged for the purpose of recording theampere-squared-seconds of spot welding current impulses; Fig. 2 showsdetails of the chartadvancing rolls; and Fig. 3 shows how a markingfeature of the recorder may be varied.

In the drawing, it represents the power cables leading to the electrodesi2 of spot welding equipment. The control apparatus which is generallyprovided in the power supply to electric Welding operations.

shown is that embodying the present invention for measuring andrecording a quantity proportional to the heat energy consumed in thewelding operations at the electrodes for consecutive These weldingoperations may be repeated as often as one hundred times or more aminute, and each operation is accompanied by a current surge throughleads iii. The apparatus of my invention responds to these currentsurges to produce individual records of the ampere-squared-secondsenergy of each surge. This requires that the measuring and recording ofa given surge must be completed in a time interval of less than onesecond in duration and the apparatus conditioned to measure and recordthe next surge. The more important aspects of my invention concernfeatures which enable the electric measuring and recording apparatus toperform their functions accurately in the short time periods mentioned.

In the circuit of one of the power leads I0 is represented a currenttransformer ll of a high current reducing ratio. The secondary of thetransformer supplies greatly reduced but proportional current impulsesto a relay l2 and to the measuring coil l3 of a recording galvanom eter.The purpose of relay l2 and the vacuum tube and relay circuits showngenerally above this relay are primary to control the timing of therecording operation and the reconditioning of the .galvanometer aftereach surge measurement. However, before attempting a detail explanationthereof, it will be best to describe the galvanometer recorder.

The .galvanometer comprises essentially three parts, first a measuringelement energized by coil 13, and having a two-pole stationary magnet Itand a two-pole magnetic armature l5 secured to the rotary shaft 16;second, a damping element consisting of a disk I! of conducting materialsecured to shaft l6 and one or more stationary permanent magnets iswhich convey a damping flux through the disk H for damping purposes; andthird, a zero return element consisting of a two-pole magnetic vane l-Qsecured to shaft 56 and a two-pole stationary field magnet '29 whichWhen energized tends to turn its vane it into alignment with its polepieces at approximately the zero position of the shaft IE. A recordingarm 2! is secured to shaft i6, and its outer end extends freely betweena record sheet 22 and a printing .rod 23.

The record printing apparatus may comprise a printing platten 24 in theform. of a roller Welders is not shown. The apparatus Which is 55beneath the printing rod 23. About drum 2i is a belt of carbon paper orits equivalent. The record sheet 22 is preferably sufficiently thin asto be transparent so that when the printing rod 23 forces pointer 2|down against the printing platten with the record sheet and carbon paperintervening, a mark is made on the under surface of the record sheet ofthe position of pointer 2|, which mark is visible through thetransparent sheet. 26 represents a supply roll for the record sheet, and23 a driving drum for the record sheet. 29 is a small timing motor usedfor driving the drum 28 for advancing the chart 22. The advance of chart22 rotates roller 24 and since the carbon paper belt 25 is about roller24 in contact with chart 22 the carbon paper belt 25 is also advanced bymotor 29. The carbon paper belt 25 is advanced over roller 24 at aboutthe same rate as the record sheet is advanced above it, but, exceptduring the instance of printing, the carbon paper does not transfermarking material to the record sheet.

In order automatically to stop the advance of the record sheet whenwelding operations are temporarily discontinued, I have provided aspecial contact device for opening the circuit of the timing motor 29.The contacts of this device comprise a metal wheel 3| and a resilientmetal brush 32 hearing against the wheel 3| and included in the circuitof motor 29.

As here shown, the metal wheel 3| is urged in a counterclockwisedirection by a light spiral spring 33 and has an insulating finger 34extending from its periphery which, if rotated clockwise against theupper end of contact 32, forces the contact away from wheel 3| to openthe circuit of the timing motor 29. This contact mechanism is pivotallymounted at 2'! and is connected with the armature 35 of a relay 36 byrod 3|]. This relay 36 is energized following the occurrence of awelding surge as will be described subsequently. When the relay 36 isdeenergized, the metal wheel 3| is rotated in a clockwise directionsince it is on a shaft geared at Eta to the shaft of roller 28 driven bytiming motor 29 and in this condition, which is that represented in thedrawing, wheel 3| will be driven clockwise so long as the timing gotorremains energized through contacts 3| and It is seen that in a shorttime interval, if the relay 35 is not energized, insulating finger 34will rotate against spring finger 32 and move it away from wheel 3! tobreak the timing motor circuit.

This condition of afiairs will remain until relay 36 is energized. Whenthis happens the contact assembly is swung to the right about pivot 21and the gears at 23a are separated. Now spring 33, which has been woundup, can rotate 3| counterclockwise until finger 34 is stopped by contactwith a stop 3 5a. Finger 32 is now in contact with wheel 3| and thetiming motor starts in operation to advance the record sheet. Ordinarilywhen surges to be recorded are coming in at a rate of say once persecond, the finger 34 does not reach contact 32 but is repeatedlyreturned against its stop and the timing motor circuit remains energizedto advance the record sheet continuously, but as soon as relay 3%remains deenergized for a somewhat longer period, which period may bemade anything desired, the timing motor circuit is again opened andremains open until the next surge to be recorded occurs. It will beevident that with this arrangement the record sheet will always beadvanced so as to leave a clean portion of the record sheet in recordingposition when the motor stops and hence the first impulse that comes inand starts the timing motor will be properly recorded. This expedientnot only saves considerable recording and carbon paper, but it saveswear and tear on the recording apparatus and useless operation of thetiming motor. Delays incident to renewing the recording paper supply arereduced, and the records which are obtained are condensed and easier tostudy than if scattered over an unnecessary length of record sheet,

The printing rod 23 extends over the recording swing of pointer 2| andmay be resiliently suspended and provided with a magnet 38 which will bemomentarily energized at the proper time, as hereinafter explained, toperform a recording operation.

The deflecting, damping and zero return torques of the recorder arelarge in comparison with the moment of inertia of the moving partsmounted on shaft l6.

In the iron vane type of measuring instrument here used the deflectingtorque is proportional to the square of the current (I) flowing in itscoil l3. The damping torque is proportional to the angular velocity (w)which is equal to a damping constant K times I The angular travel of thepointer from a zero position, when there is no zero restoring torque andneglecting friction and moment of inertia, is equal to the averageangular velocity K1 multiplied by the time duration (t) of the surge.The moment of inertia of the moving parts of the instrument is madesmall in comparison with the torques referred to and therefore does notmaterially alter the deflection characteristics of the instrument, butto the extent that it does it may be compensated for according to thefollowing explanation. That small portion of the up-scale torque of theinstrument during acceleration of the pointer up-scale, which is used upin overcoming the inertia of the moving parts is substantiallyequivalent to the kinetic energy remaining in the moving parts when theup-scale torque ceases. This will cause the pointer to oontinueeto bemoved up-scale until this energy is used up by the opposing dampingtorque. If then at the end of a surge we allow pointer 2| to moveup-scale until it steps before we print the record, the recordingposition of the pointer will be proportional to 1% within a negligibledegree of error. If the surge is of relatively low current value theacceleration and deceleration forces of the moving parts will both becorrespondingly small. If the surge is of a relatively high currentvalue the acceleration and deceleration forces will both becorrespondingly large so that as long as we allow the pointer to come torest before the record is printed the recording position will beporportional to Ft. The zero return magnet 28 is energized from aconstant voltage source and hence produces a zero return torque which isconstant for a given deflection and is proportional to the up-scaledeflections and reduces to approximately a zero value at the zeroposition of the shaft.

I provide a timing system responsive to the operation of relay |2 fordelaying the printing of the position of the recording arm 2| for asuitable period after the end of each surge and also for controlling thetime sequence of operations necessary to print the record and restorethe printing arm to a zero position in readiness for the next surge.

' The timing system and the relays controlled thereby are supplied by aconstant voltage source 45 which, for the condenser and resistancevalues hereinafter mentioned by way of example, may be a 220 volt, 60cycle, A. C. source.

Connected across source 4!) is a relay M, a vacuum tube-A2, and a 2microfar-ad supply-condenser 43 in series relation. When-current flowsthrough this circuit, relay 4| is energized and condenser 53, if notby-passed, is charged.

Surge responsive relay 12 operates a threepole double throw switch M,the primary pura stop 51 of its moving system resting against a '-zerostop 58.

To assist in explaining the operation of the apparatus there follows anapproximate time table of events during -a surge cycle. The first columnof the table gives the timing of the events starting with the steadystate condition. The several other columns indicate the condition of thedifferent elements identified at the head of pose of which is to connecta 0.1 microfarad 1-0 each'co'lumn at the different times indicated.transfer condenser 45 and a 0.3 microfarad trans- The first horizontalline of the table below the fer condenser 46 across condenser 43 totransfer identifying headings gives the steady state or a portion of thecharge on supply condenser d3 idle condition mentioned above, and thisis the to the smaller condensers 45 and 85 when a surge condition of theapparatus as shown in Fig. 1.

Relay Currents Condenser voltages Coil currents Time I 12 41 48 as as 4345 4s 13 20 MiZli- Milli- Milli- AHIYPETBS amperes amperes [11711)5768amperes Steady state. O 20 0 0 .300 0 0 0 0 Surge starts 5 Neg. 0 0 240'240 240 6 0 Surge stops 0 0 0 0 0 0 240 240 0 0 lsec. later 0 20 0Energized. Energized, 0 orless 150 o o .11 sec. after surge stops 0 2O 0d0 0 0 0 1.25 0 30 .4 sec.aftersurge stops 0 20 20 .do 0 l0 0' 30 orless. 0 30 .5 sec. after surge stops 0 0 2O 0 0 300 0 0 0 starts and toconnect condenser 45 across the In the steady state condition relay 48is enerfilament and the control grid of vacuum tube 42 gized by about2.0 milliamperes. All of the other and condenser 46 across the filamentand the con- 30 relays 'andcoils indicated are deenergized. Control gridof a vacuum tube 41 when the surge denser 43 has a charge of about 300volts since has ended. it tends to charge up to the peak voltage of theIn the energized position of relay H! the con- 220 volt A. C. sourcefifl. When a surge starts nections of this switch, as first mentionedabove, the conditions indicated in the next line of the are made throughthe upper stationary contacts table exist. Relay i2 is energized andoperates of the switch 44, and when relay 12 is deenerswitch 45 to theraised position and the charge gized, which is the condition shown, thesecond on condenser 43 is distributed between all three mentionedconnections are made through the condensers to give voltages of about240. There lower sets of stationary ccntacts of switch M. may be someslight flow of current through tube Vacuum tube 47 is connected acrosssource as '42 because of this lowering in voltage but not in series witha relay 68 having contacts arranged enough to operate relay M, and itscurrent is to by-pass and discharge condenser 43 through at indicated asbeing negligible. 100 ohm resistance 49 when relay 48 is deener- Thesurge current flows through galvanometer gizei coil 13 and relay coill2, and its value has been It will also be noted that when switch 44 isin 45 indicated as 5 amperes, which may be considered the deenergizedposition shown and condensers 'a normal surge value in the currenttransformer 45 and 46 are connected to bias the tubes 42 and secondary,but it will be understood that this :1! respectively, the biasingcharges of these concurrent may vary in accordance with the primarydensers leak off through megohm resistances surge current value. Thegalvanometer of course 58 and 5! respectively, which resistances are at5 now starts to move the recording pointer upthis time connected acrosscondensers 45 and 46 scale until the surge stops and we arrive at therespectively, condition shown in line three of the table. The

Stabilizing resistances of about megohm each length of the surge mayvary. A common length are connected in the grid leads of tubes 42 and-EJ 51001? We ding current surge is six cy es of a 4? cycle frequency.When the impulse stops (line Relay M when energized energizes relay 36three of the table) relay l and coil l3 are dethrough wire 52, andprinting relay 38 through energized. Switch 44 drops to the lowerconcontact 53 of relay 3.6 and wire 54. Relay 36 in wets- T e 240 voltcharge on condenser 46 is addition to performing the function previouslyimpressed across filament and grid of tube M described in connectionwith the control of the m in a dire n o p c rren w therethrou-gh timingmotor 29 Serves when engrgized t open and relay 48 is deenergized, andthis short-circuits t circuit of printing relay 33 and t close thcondenser 43 through resistance 49 and the voltcircuit of the zeroreturn magnet 29 of the reage f onden 3 drops p y w rd the cordingmeter, through a contact 55 and wire 56. Zero Value indicated The 240V0117 charge n In the idle or steady state condition of the timcondensers p essed between filament and ing system, relays l2, 4!, 36 33 d Zeroreturn grid of tube 42 and is in a direction to hold this magnet it willbe deenergized. Tube 41 which tube at cut is connected directly acrosssource GE] through the The damping element of the galvanometer is coilof relay 48 will be passing current and relay bringing e lip-Scalemovement of the 48 will be energized. Condenser 43 will be charged1301111761 a ll About one-tenth second later and condensers 45 and 4sdischarggd d th the conditions in line four of the table will exist. layconnections will be as represented in Fig. l. a ge on Condenser 45 hasleaked off No surge current will be flowing in the instrument throughres s ce 3 until its C e is 30 Volts coil l3 or in the coil of relay i2,and the galvaor less and tube i2 is no longer held at out off nometerpointer will stand in azero position with and passes about 20milliamperes current through resistance 49, the closed contacts ofdeenergized relay 48 and the coil of relay 4|. Relay 4| is energized andhas closed its contacts and has energized normally deenergized printrelay 38 which prints the position of the now stationary pointer 2| atthe top of its swing. Relay 36 which is slow acting as compared to theprint relay is energized and has just started pulling in its armature.The conditions rapidly change to those indicated in line five of thetable at about .11 second after the surge has stopped. Here relay 33 hascompleted its pull in operation and deenergized print relay 38 andmomentarily energized the coil of the normally deenergized zero returndevice 20, which starts returning pointer 2| towards a zero positionwith a torque proportional to the pointer deflection from zero. Thecharge on condenser 46 has been leaking off through resistance but tube41 is still held at cut 01f.

.4 second after the surge stops the conditions in line six of the tablewill exist. The pointer has been returned to zero position against stop58, with the return coil still energized but now in a rotary positionwhere its returning torque is very small and nearly of a zero value.This, together with the checking action of the magnetic damping element,has quickly brought the pointer to a zero position yet without shock andwithout tendency to bounce away from the stop. The charge on condenser43 has leaked away until tube 4'! passes current, relay 48 is energizedand the current through tube 42 and relay 4|, instead of being by-passedthrough the contacts of relay 48, starts to charge condenser 43 and hasdropped somewhat below ma. but is still sufi'icient to maintain relay 4|in its energized position. One-half second after the surge has stopped,the conditions in line seven of the table will exist. At this timecondenser 43 has become substantially charged, the flow of currentthrough tube 42 and relay 4| has stopped or dropped to a negligiblevalue, and the contacts of relay 4| are open, relay 36 is deenergizedand returned to open position, thereby deenergizing the zero returndevice 20. This returns the apparatus to the steady state condition uponcompleting the cycle of events and the apparatus is in readiness torecord the next surge.

It is seen that this cycle is completed in onehalf second after thesurge stops. Assuming the average length of surge is one-tenth second induration, a normal surge may occur and be re- I corded and the apparatusconditioned for recording the next surge in 0.6 second. Thus surges ofthe character contemplated may occur at the rate of 100 per minute andbe measured and recorded by this apparatus adjusted as above described.It will be understood that the timing cycle may be changed by changingthe times required for condensers 45 and 46 to discharge and remove thecut off bias on tubes 42 and 41. For example, to decrease the time delaycaused by condenser 45 and tube 41 I may either reduce the value ofcondenser 46 or give it a higher discharge rate by decreasing resistance5|. Also the time delay intervals of both tubes 42 and 41 may be reducedby reducing the capacity of condenser 43. This will result in a lowerinitial charge on condensers 45 and 46 and hence give them a shorterdischarge interval. These and other adjustments may be made to vary thetiming sequence and while certain circuit constants and timingconditions have been given by way of example, the invention is notlimited to the particular time cycle of adjustment described.

So long as surges come in frequently, the timing motor 29 will remain inoperation, but if the surges cease occurring frequently the time delaymeans consisting of finger 34 of contact wheel 3| will, after a shorttime delay, rotate into contact with resilient contact 32 to open thetiming motor circuit and stop the advance of the recording paper.

The welding circuit is usually controlled by a vacuum tube apparatus(not shown) such that a welding surge lasts for a definite number ofcycles. If anything happens to such control apparatus to shorten orlengthen the surge, or if such control apparatus becomes defective tovary the voltage across the electrodes or to skip a portion of thenormal surge, while conditions at the welding electrodes remain normalthe increase or decrease in the 1% product measured and recorded by mysurge recorder will immediately show up by the records produced.Likewise, if the power control apparatus functions properly but theresistance between the weld electrodes incident to a welding operationvaries from normal due to failure of proper contact pressure, improperspacing of electrodes or defective material being welded so as to changethe factor I in the product measured by the recorder apparatus, suchdefective condition will be immediately revealed by the variation fromnormal of the records obtained. Similarly if the line supply voltagevaries to affect I it will be revealed in the record.

The nature of the records obtained are shown by the dots indicated at 60on record sheet 22. As illustrated, the printing rod 23 is provided witha removable or adjustable section 6| of insulating material such asrubber. At the lateral boundaries of this insulated section there areprovided raised printing ridges 62, which, when the printing relay 38 isenergized, print boundary lines 63 on the record sheet 22 when therecords 60 are printed.

The front section 64 of the printing rod which holds rubber part 6| andthe boundary printing ridges 62 is either removable or adjustable. In

Y the example shown, the adjustable part 64 is fastened to the main part23 of the printing rod by screws 65. When these screws are removed, part64 with insulating part 6| and the boundary printing ridges may be movedlaterally or removed entirely and replaced by another section 64' (seeFig. 3) having the insulated part 6| wider or narrower than the part 6|of Fig. 1 or at a different lateral position or both and with boundaryprinting ridges 62' at its lateral edges. The boundary printing lines 63are helpful in the calibration and use of the apparatus. These lines areso spaced with respect to the calibration of the instrument as to markthe upper and lower limits'of satisfactory welding surges and so long asthe records fall between these lines, as shown for example by therecords 6!! in Fig. 1, the welder is assured that the welding surgescontain the proper amount of heat energy to give satisfactory welds.

If the records 63 go lower as at point 68a or higher as at point Bill)than the limits set, it may be assumed that something is wrong with thepower control apparatus or the welding apparatus, and the trouble shouldbe located and ass-ans corrected before further welding operations aremade. a

If pointer 21 is outside the boundary limits 62' when a record is madesuch as at 68a or 601), the pointer is opposite a conducting portion ofthe printing rod and an electric contact is made between the metalpointer and metal rod at the instant of printing. This contactarrangement is included in a circuit which may include one or more ofthe following: a visual signal 66-, an audible signal 61, a controlrelay 68-, aswell' as. a source of supply 69. The relay 68 may bearranged to shut off the power supply to the welder so that no furtheruse thereof may proceed until the apparatus has been checked and thecondition corrected. When the pointer is opposite the insulated pa-rt 6|when the record is printed the lower edge of the insulated part strikesthe pointer and hence the signal or control circuit is not energized forsatisfactory welding surges. The connection of the signalling circult tothe recording pointer shaft should be through a connection such as aweak spiral which has negligible turning effect on the shaft in anyposition.

In order to avoid.- trouble with the carbon paper belt 25 and recordpaper 22, I have found that certain precautions, are very desirable. Itis difficult to provide a carbon paper or cloth belt 25 of exactly thesame length at both ends. For example, the belt may be formed by a sheetof carbon paper of the desired width and length which, when the ends arepasted together, form a belt. In pasting the ends of the sheet togetherto form a belt, one peripheral side of the belt may be found to be inchlonger than the other in spite of care being taken to prevent any suchdiscrepancy. Such a belt when simply placed on parallel rollers such asthe rollers 24 and Ill and driven as here contemplated, will not runtrue but will invariably work endwise towards that end of the belt whichis the longest. Even collars such as collars ll shown at the ends ofroller 24 will not prevent an uneven belt of carbon paper from workingendwise and climbing out over such collar. This troublesome difiicultyhas been overcome by the use of a wrinkle bar 12 having bends l3 beneaththe paper belt near the ends of such belt where it is fed onto roller24. These bends crowd the end edges of the paper belt inward and causeit to wrinkle up slightly just as it passes into platten roller 24 andthe belt is made sufficiently loose to permit this without tearing. Whenthe belt passes over roller 24, the chart paper 22 is outside and undersufficient tension to drive the carbon paper belt and to flatten out thewrinkles in and without causing creasing of the carbon paper. Thispressing and driving action of chart 22 on the carbon paper over alimited periphery of roller 24 allows the belt to adjust itself, thewrinkles in the long end of the belt apparently being pressed out in aforward direction and the wrinkles in the short end of the beltapparently being pressed out in a retarding direction to the extentnecessary to allow an uneven belt to be driven without working endwise.Actually, the long end of the belt is driven faster than the short end,due to the adjustment allowed incident to the smoothing out of thewrinkles to the extent necessary to compensate for the difference inperipheral length of the belt at its opposite ends.

The chart 22 used is a relatively thin lightweight paper in order thatit will be sufficiently transparent to enable the records, which aremade on the. under side of the chart, to be. clearly visible.therethrough. It is impracticable to drive such. a chart with a tootheddrum'having driving teeth projecting through holes punched alongtheedges of the chart. The chart driving arrangement used, and which hasbeen referred to generally above. as a driving drum 23, requires somefurther explanation. The driving drum 2% may be constructed as indicatedin Fig. 2 having a-soft rubber cylindrical driving, section 14 at its.

center and soft rubber inwardly tapered guiding sections f5 at its twoends. The remainder of this drum ismade of reduced diameter and may bemade up' of metal parts which serve as supporting and spacing parts, butdo not enter into driving contact with the paper. Beneath driving drum28 is another drum made up of a long central part it and short end partsTl. These three parts are so supported as to be freely rotatableindependently of each other. Part 16- is pressed in driving contact withsuction part T4 of drum 28 and the chart is gripped between these twoparts and they constitute the main driving elements of the arrangement.End roller parts 1-! are slightly smaller in diameter than part T6 andthey are in driving contact with the outer cylindrical portions ofsuction guide roller parts 15; The maximum diameter of parts 15 isslightly greater than the diameter of cylindrical part H, but theminimum diameters of these parts are the same. The chart is of a widthequal to thedistance between the inner ends of parts 15 and is normallydriven in a central position with its end edges in line with the innerends of the parts it. In case the chart tends to creep towards one sideor the other of such central position, one edge rides up on thecone-shaped surface of part 15 and there is an immediate tendency forsuch edge to be driven faster than the middle of the chart due to theincreased diameter of part 15 and the fact that parts l4. and 15 aredriven at the same speed. This straightens the chart and returns it to acentral driving position. This correcting effect of the coneshapedroller parts ":5 at any instant is in proportion to extent of chartdisplacement from a central position at the driving drum. Guide collarsH maintain the chart properly centered under the recording position andhence such correcting effects as occur at the driving drum do notdisplace the record on the chart.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Surge responsive circuit control means comprising in combination withthe circuit to be controlled, a grid controlled vacuum tube and astorage condenser in series relation in said circuit, a transfercondenser, a transfer switch op erated in one direction in response tothe beginning of a surge for connecting said condensers in parallel toequalize the voltages thereon and operated in the opposite direction inresponse to the ending of a surge for impressing the voltage of thetransfer condenser on the grid of said tube to bias it to cut off and toestablish a circuit across said transfer condenser for discharging itand thus rendering said tube conducting in a predetermined fraction of asecond, and other means responsive to the last mentioned operation ofsaid transfer switch for discharging said supply condenser so that assoon as said tube becomes conducting said circuit will be energizedtherethrough' and remain energized until said supply condenser isrecharged.

2. Surge responsive control means including a.

circuit to be controlled comprising a vacuum tube and a supply condenserin series relation, a normally energized relay which when deenergizedestablishes a short circuit about said supply condenser, a second vacuumtube in series with the normally energized relay, a pair of transfercondensers smaller than the first mentioned condenser, a transfer switchoperated in response to a surge for connecting said transfer condensersacross said supply condenser and operated in response to the cessationof a surge to disconnect said condensers from each other and connect thetransfer condensers to produce cut off biasing voltages on said twovacuum tubes, and means for gradually discharging said transfercondensers when connected as last mentioned. 3. Surge responsive timingmeans for controlling a circuit in timed relation with a surge, saidmeans including the circuit to be controlled, a grid controlled vacuumtube and a supply condenser in said circuit, a normally energized relaywhich when deenergized closes a discharge circuit across said supplycondenser, a circuit including the energizing Winding of the normallyenergized relay and a second grid controlled vacuum tube, a pair oftransfer condensers, a transfer switch, means responsive to a surge foroperating said transfer switch to connect the three condensers inparallel to transfer charges from thesupply condenser to the transfercondensers and to disconnect said condensers and connect the supplycondensers to bias the grids of said vacuum tubes to out off when thesurge ceases, resistance discharge circuits for said transfer condenserscompleted when said condensers are connected to bias said tubes, thetube included in the circuit to be controlled becoming conductive, firstto determine the time of energizing of the control circuit and the othertube becoming conducting thereafter to determine the time ofdeenergizing of the control circuit.

4. In combination with a control circuit, timing means for controllingsaid circuit in timed relation with current surges, said means includinga grid controlled vacuum tube and a supply condenser connected in seriesrelation in said I circuit, a normally energized relay which whendeenergized closes a discharge circuit across said supply condenser, asecond grid controlled vacuum tube in series with said relay, a pair oftransfer condensers, a transfer switch, surge responsive means foroperating said transfer switch to connect said condensers in parallelwhen a surge starts and interrupting said parallel connection, andindividually connecting the transfer condensers to the control grids ofthe two tubes to bias said tubes to out off when a surge stops,resistance discharge circuits for said transfer condensers, completedwhen a surge stops, to progressively remove the grid bias of the firstand second mentioned tubes at predetermined different times after asurge stops to cause the timed energizing and deenergizing of thecontrol circuit.

THEODORE A. RICH.

